The present invention relates to color control of real time digital video images and, more particularly, to a method for independently controlling hue or saturation of individual colors in a real time digital video image, without affecting the hue and saturation of any other color in the same real time digital video image.
Controlling colors in a displayed real time digital video image is typically performed by changing the hue, and/or, by increasing or decreasing the saturation of the colors or color components of the real time digital video image. Herein, an xe2x80x98individual colorxe2x80x99 represents a linear combination of colors or color components, such as red, green, blue, yellow, cyan, and magenta, where, in RGB color space, the basic colors or color components are red, green, and blue, which are used for defining and evaluating the complementary colors or color components yellow, cyan, and magenta, and, in YCM color space, the basic colors or color components are yellow, cyan, and magenta, which are used for defining and evaluating the complementary colors or color components red, green, and blue. Herein, the term xe2x80x98huexe2x80x99 refers to the angle between one color or color component and other colors or color components characterized in a particular color space, for example, RGB color space, featuring a color based three-dimensional coordinate system, within a real time digital video input image. Hue is also referred to as tint, or, as a gradation or shade of a color or color component. Herein, the term xe2x80x98saturationxe2x80x99 refers to the intensity of a color or color component characterized in a particular color space, for example, RGB color space, featuring a color based three-dimensional coordinate system, within a real time digital video input image. Saturation is also referred to as vividness of hue.
Different formats are used for characterizing colors or color components in real time digital video images. In one format, real time digital video images feature colors or color components characterized by linear combinations of the basic colors red, green, and blue, in RGB color space. In another format, real time digital video images feature colors or color components characterized by linear combinations of the basic colors yellow, cyan, and magenta, in YCM color space. In still another format, real time digital video images feature colors or color components characterized by linear combinations of the chromatic parts, Cr and Cb, also known in the art as U and V, respectively, in YCrCb or YUV luminance/chromatic color space, respectively. As is well known in the art, one format of a real time digital video image display can be transformed to another format by using appropriate linear combination functions.
In applications involving display of a real time digital video image, a user may desire to adjust or change the hue or saturation of an individual (single) color or color component of the real time digital video image, without affecting the hue or saturation of any other color or color component of the same real time digital video image. For example, a user may desire to adjust the hue or saturation of only one color, such as red, green, blue, yellow, magenta, or, cyan, of a real time digital video image displayed on a television screen, by pushing or turning a color hue or color saturation or intensity control button or dial on a control device associated with the television screen. Unfortunately, however, controlling hue or saturation of an individual color by this procedure affects the hue and/or saturation of all the colors or color components of the television image, and not just the hue or saturation of the individual color desired to be changed by the user.
In PCT International Patent Application Publication No. WO/00052938, published Sep. 08, 2000, taking priority from U.S. patent application Ser. No. 09/261,193, filed Mar. 03, 1999, now U.S. Pat. No. 6,122,012, by the same inventor of the present invention, there is disclosed a xe2x80x9cMethod Of Selective Color Control Of Digital Video Imagesxe2x80x9d. The disclosed method features using simple Look-Up-Tables (LUTs), whose values are calculated from uniquely defined color control functions, to digitally change the saturation or intensity of a single color of the chromatic part of a digital video image without affecting the saturation or intensity of any other color of the chromatic part of the same digital video image. A digital video input image is scanned, row by row, pixel by pixel. Each input image pixel value, defined from the chromatic part of the digital video input image, is assigned an address to be operated on by values in individual color LUTs. For a desired change in an individual color of that image, a new digital video output image is produced featuring the desired change in the individual color without affecting the remaining colors of that same image. Application of the disclosed method to display of digital video images precludes the need to convert video components (for example, YCrCb) into RGB (red, green, blue) components.
Selective color control using the just described method enables viewers of real time digital video images to do two things currently not achievable using conventional methods of color control of real time digital video images. Firstly, to very accurately set or adjust individual colors of a given real time digital video image to the actual colors of the subject of the image, and, secondly, to very accurately modify or alter colors of a given video image to produce desired special effects in that real time digital video image.
However, the just described method is notably limited because there is description of selectively controlling only the saturation or intensity, and not the hue, of individual colors of real time digital video images. Additionally, the disclosed method is based on using an algorithm which is particularly described with respect to real time digital video images featuring colors or color components characterized by linear combinations of the chromatic parts, Cr and Cb, or, U and V, in YCrCb or YUV luminance/chromatic color space, and there is no particular description with respect to other formats of real time digital video images, such as the RGB or YCM color space formats.
To date, the inventor is not aware of prior art teaching of a method for independently controlling hue of individual colors in a real time digital video image, without affecting the hue and/or saturation of other colors in the same real time digital video image.
There is thus a need for, and it would be highly advantageous to have a method for independently controlling hue or saturation of individual colors in a real time digital video image, without affecting the hue or saturation of any other color in the same real time digital video image. Moreover, there is a need for such a method for controlling color of real time digital video images which is efficient and robust, and is particularly applicable to real time digital video images featuring colors or color components characterized by linear combinations of the basic colors of red, green, and blue, in RGB color space.
The present invention relates to a method for independently controlling hue or saturation of individual colors in a real time digital video image, without affecting the hue or saturation of any other color in the same real time digital video image.
Thus, according to the present invention, there is provided a method for independently controlling hue or saturation of individual colors in a real time digital video image, comprising the steps of: (a) receiving and characterizing the real time digital video input image featuring input image pixels; (b) selecting to independently change the hue or the saturation of an individual color in the real time digital video input image, by selecting an independent color hue control delta value or an independent color saturation control delta value, respectively, wherein the independent color hue control delta value represents an extent of change in the hue of the selected individual color and wherein the independent color saturation control delta value represents an extent of change in the saturation of the selected individual color; (c) identifying a plurality of the input image pixels having the selected individual color in the real time digital video input image with the hue or the saturation selected to be independently changed, by performing arithmetic and logical operations using input image pixel values of each input image pixel of the real time digital video input image; (d) determining corresponding output image pixel values for each of the plurality of the input image pixels identified as having the selected individual color in the real time digital video input image with the hue or the saturation selected to be independently changed, by separately evaluating independent color hue control functions or independent color saturation control functions, respectively, using the input image pixel values of the plurality of the input image pixels, and using corresponding selected independent color hue control delta value or the corresponding selected independent color saturation control delta value, for forming a corresponding plurality of output image pixels having the selected individual color with the hue or the saturation selected to be independently changed; and (e) displaying a real time digital video output image including the corresponding plurality of the output image pixels having the selected individual color with the hue or the saturation selected to be independently changed in the real time digital video input image, whereby the hue or the saturation of the selected individual color in the real time digital video input image has been changed without affecting the hue or the saturation of any other individual color in the real time digital video input image.
According to another aspect of the present invention, there is provided a system for independently controlling hue or saturation of individual colors in a real time digital video image, comprising: (a) a real time digital video image display device displaying the real time digital video image featuring input image pixels; (b) a master control device in operative electronic communication with and controlling the real time digital video image display device; and (c) a viewer of the real time digital video image display device operating the master control device for selecting to independently change the hue or the saturation of an individual color in the real time digital video input image, by selecting an independent color hue control delta value or an independent color saturation control delta value featured on the master control device, respectively, wherein the independent color hue control delta value represents an extent of change in the hue of the selected individual color and wherein the independent color saturation control delta value represents an extent of change in the saturation of the selected individual color, whereby the real time digital video image display device in the operative electronic communication with the master control device performs steps including: (i) identifying a plurality of the input image pixels having the selected individual color in the real time digital video input image with the hue or the saturation selected to be independently changed, by performing arithmetic and logical operations using input image pixel values of each input image pixel of the real time digital video input image; (ii) determining corresponding output image pixel values for each of the plurality of the input image pixels identified as having the selected individual color in the real time digital video input image with the hue or the saturation selected to be independently changed, by separately evaluating independent color hue control functions or independent color saturation control functions, respectively, using the input image pixel values of the plurality of the input image pixels, and using corresponding selected independent color hue control delta value or the corresponding selected independent color saturation control delta value, for forming a corresponding plurality of output image pixels having the selected individual color with the hue or the saturation selected to be independently changed; and (iii) displaying a real time digital video output image including the corresponding plurality of the output image pixels having the selected individual color with the hue or the saturation selected to be independently changed in the real time digital video input image, whereby the hue or the saturation of the selected individual color in the real time digital video input image has been changed without affecting the hue or the saturation of any other individual color in the real time digital video input image.
According to further features in preferred embodiments of the invention described below, the real time digital video input image is of a format selected from the group consisting of RGB format, YCrCb format, and, YUV format, whereby the individual colors of one format can be characterized by the individual colors of a second format by using appropriate linear transformations between the formats.
According to further features in preferred embodiments of the invention described below, the real time digital video input image features basic colors red, green, and blue, and, complementary colors yellow, cyan, and magenta, in RGB color space, whereby values of the complementary colors are expressed in terms of and evaluated from linear combinations of values of the basic colors.
According to further features in preferred embodiments of the invention described below, the real time digital video input image features basic colors yellow, cyan, and magenta, and, complementary colors red, green, and blue, in YCM color space, whereby values of the complementary colors are expressed in terms of and evaluated from linear combinations of values of the basic colors.
The present invention successfully overcomes limitations of presently known techniques and methods for real time controlling color, in general, and independently controlling color components such as hue and saturation, in particular, of real time digital video images. Independently controlling hue or saturation of individual colors in a real time digital video image, without affecting the hue or saturation of any other color in the same real time digital video image, enables viewers of video images to do two things currently not achievable using conventional methods for controlling color of real time digital video images. Firstly, to very accurately, yet independently, change or adjust the hue or saturation of individual colors of a given real time digital video image according to the actual hue or saturation of individual colors of the subject of the real time digital video image, and, secondly, to very accurately, yet independently, modify or alter the hue or saturation of individual colors of a given video image to produce desired special effects in the real time digital video image. These benefits of the present invention are immediately applicable to the television and movie industries, where it is critically important for real time digital video images to represent actual hue or saturation of individual colors of a real time digital video image, and to have the capability of producing special effects to real time digital video images.
Implementation of the method of the present invention for independently controlling hue or saturation of individual colors in a real time digital video image, without affecting the hue or saturation of any other color in the same real time digital video image involves performing or completing selected tasks or steps manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and/or equipment used for implementing a particular preferred embodiment of the disclosed method, several selected steps of the present invention could be performed by hardware, by software on any operating system of any firmware, or a combination thereof. In particular, as hardware, selected steps of the invention could be performed by a computerized network, a computer, a computer chip, an electronic circuit, hard-wired circuitry, or a combination thereof, involving any number of digital and/or analog, electrical and/or electronic, components, operations, and protocols. Additionally, or alternatively, as software, selected steps of the invention could be performed by a data processor, such as a computing platform, executing a plurality of computer program types of software instructions or protocols using any suitable computer operating system.